Home > Companies > Colinwell Masonry > AB One (1° Setback)

Allan Block is a hollow-core, dry-stacking concrete block for the construction of retaining walls. Designed with a 1° raised front lip which automatically establishes the setback from vertical.

Manufactured from a mixture of aggregates (65% recycled secondary aggregate content) and cement.

Features and benefits:

  • Cost-effective and versatile.
  • Offers high performance, quality, and lasting value.
  • Expected lifespan of 120 years (if designed and built in accordance with its British Board of Agrément (BBA), Roads and Bridges certificate).
  • Includes a hollow-core design which makes blocks easy to handle, promotes drainage and becomes solid when filled with stone.
  • Anti-climb.
  • No need for pins, clips or mortar.
  • Can be constructed regardless of weather conditions.
  • Built-in drainage.
  • Durable and maintenance-free.
  • Freeze-thaw resistance.
  • High strength, durable block.
  • Efflorescence-free.


Suitable for:

  • All types of road and rail infrastructure projects that require approval by the Highways Agency (as the product holds a BBA Roads and Bridges certificate).
  • Large commercial and residential walls.

Will require reinforcement, most often through the use of Geogrid, No-Fines Concrete or building a double-width gravity wall.

CE-marked and manufactured in accordance with BS EN 771-3, ISO 9001 and ISO 14001.

Standard product features

Size (h x w x d):

200 x 450 x 300 mm.


Split-face texture.


35 kg.

Technical characteristics:

  • Mean compressive strength: 30 N/mm².
  • Density: 2100 kg/m³.
  • Absorption rate: 3–6%.
  • Face coverage: 11.11 m² (approximately).


Accessories/ Other requirements:

- Geogrid:

Typical Geogrid reinforced walls will require an excavation depth of 70% or more of the wall height to accommodate geogrid tails.

- No-Fines Concrete:

Will require an excavation depth of around 40% of the wall height.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-80-50/300 Aggregate concrete blocks

Product specification

An important note about specifying



Colinwell Masonry


+44 (0)28 9061 8145

Product reference

AB One (1° Setback)


[Abbey blend]
[Cinder blend]
[Limestone blend]
[Pewter blend]
[Slate blend]
[Yorkstone blend]

Accessories/ Other requirements

[Not required]
[AB Corner Block]
200 x 400 x 200 mm (h x w x d), 26 kg (available left- or right-handed; insert requirements).
[AB Wall Caps]
100 x 450 x 300 mm (h x w x d), 27 kg (to be fixed with a high-grade, waterproof, flexible masonry adhesive).
For use when the block weight and setback do not provide enough structural support. For taller walls. Consult manufacturer for information.
[No-Fines Concrete Backfill]
Will allow taller walls to be constructed with less excavation. For taller walls. Consult manufacturer for information.

Manufacturer details

37 Colinglen Road,
Co Antrim, BT17 0LP
Tel +44 (0)28 9061 8145
Fax +44 (0)28 9062 4240
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